cope.) 444 [May 19, 



tlial the additional facet of the astragalus is produced. Its relations will 

 therefore be considered rather than those of the astragalus in framing the 

 following definitions : 



Order I. Scaphoides supported by trapezoides and not by magnum, 

 which supports lunar. Cuboid articulating proximally with calcaneum 

 only Taxeopoda. 



Order II. gcaphoides supported by trapezoides, and not by magnum, 

 which supports lunar. Cuboid extended inwards and articulating with 

 the distal face of the navicular Prohoscidea. 



Order III. Scaphoides supported by trapezoides and not by magnum, 

 which with unciform, supports the lunar. Cuboid extended inwards and 

 articulating with astragalus Amblypoda. 



Order IV. Scaphoides supported by magnum, which with the unciform 

 also supports the lunar. Cuboid extended inwards so as to articulate with 

 the astragalus Diplarthra. 



The sub-orders are defined as follows : 



I. TAXEOPODA. 



There are two, perhaps three sub-orders of the Taxeopoda; the Hyracoidea, 

 the Condylarthra, and perhaps the loxodontia* The Toxodontia are how- 

 ever not sufficiently known for final reference.f The sub-orders are de- 

 fined as follows : 



A postglenoid process ; no fibular facet of calcaneum, but an interlocking 

 articulation l)etween fibula and astragalus ; ungual phalanges trun- 

 cate Hyracoidea. 



A postglenoid process ; no fibular facets on either calcaneum or astragalus ; 



a third trochanter of the femur ; ungual phalanges acuminate 



Condylarthra. 

 There are a good many other subordinate characters which distinguish 

 the Condylarthra, which will be given in my forthcoming volume iv of 

 the Hayden Survey, on the Tertiary Vertebrata of Western America. 



II. PROBOSCIDEA. 



There may be two sub-orders of this order, the Prohoscidea and the 

 Toxodontia. I do not know the Carpus of Toxodon, l)ut if it does not differ 

 more from that of the elephants than the tarsus does ; it is not entitled 

 to subordinal distinction from the Prohoscidea. The sub-order of Pro- 

 hoscidea is defined as follows : ' 



A fibular articulation of the calcaneum ; no postglenoid process ; no third 

 trochanter of femur P'oboscidea. 



»See my remarks on Toxodon, Proceedings Amer. rhllosoph. Society, ISSl, 

 p. 402. 



t The considerable resemblance between the dentition of Toxodon and FTyrax 

 must not be overlooked. 



